Direct morning sunlight is a primary factory in attracting bats to a roost site. The availability of water and the quality and content of the surrounding habitat also play a role.
When attracting bats to an artificial roost, such as a bat house, temperature is the key factor. Eight to 10 hours of sunlight are ideal. The placement of a bat house should provide for at least six hours of direct light. In cooler climates, a dark paint or stain on the house exterior provides for adequate interior temperature. However, bat houses in warmer climates benefit from lighter exterior colors. This allows for appropriate sun exposure without risking overheating.
Bats lose water evaporatively through their wings during flight and must drink frequently. A bat house located approximately 1,500 feet from a permanent water source stands a much higher chance of attracting bats.
The diversity of the surrounding habitat also affects the success of a bat house. Bat houses positioned within 30 yards of woodlands or tree lines provide cover from predators. Nearby fields and wetlands provide for constant prey abundance throughout the bats' active season.
The size of the bat house is very important. Houses should be at least 2 feet tall with a landing area of 3 to 6 inches. Interior chambers should be 20 inches tall and 14 inches wide. Rocket box houses need to be 3 feet tall.